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Date:   Mon, 18 Sep 2023 11:03:16 +0100
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Subject: Re: [PATCH v5 6/6] drm/drm-file: Show finer-grained BO sizes in
 drm_show_memory_stats
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To:     =?UTF-8?Q?Adri=c3=a1n_Larumbe?= <adrian.larumbe@collabora.com>,
        maarten.lankhorst@linux.intel.com, mripard@kernel.org,
        tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch,
        robdclark@gmail.com, quic_abhinavk@quicinc.com,
        dmitry.baryshkov@linaro.org, sean@poorly.run,
        marijn.suijten@somainline.org, robh@kernel.org
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
        healych@amazon.com, kernel@collabora.com
References: <20230914223928.2374933-1-adrian.larumbe@collabora.com>
 <20230914223928.2374933-7-adrian.larumbe@collabora.com>
From:   Steven Price <steven.price@arm.com>
In-Reply-To: <20230914223928.2374933-7-adrian.larumbe@collabora.com>
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On 14/09/2023 23:38, Adrián Larumbe wrote:
> The current implementation will try to pick the highest available size
> display unit as soon as the BO size exceeds that of the previous
> multiplier. That can lead to loss of precision in contexts of low memory
> usage.
> 
> The new selection criteria try to preserve precision, whilst also
> increasing the display unit selection threshold to render more accurate
> values.
> 
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

I have to admit I find it odd to be "pretty printing" this value in the
first place. But this is clearly an improvement.

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
>  drivers/gpu/drm/drm_file.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 762965e3d503..34cfa128ffe5 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -872,6 +872,8 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
>  }
>  EXPORT_SYMBOL(drm_send_event);
>  
> +#define UPPER_UNIT_THRESHOLD 100
> +
>  static void print_size(struct drm_printer *p, const char *stat,
>  		       const char *region, u64 sz)
>  {
> @@ -879,7 +881,8 @@ static void print_size(struct drm_printer *p, const char *stat,
>  	unsigned u;
>  
>  	for (u = 0; u < ARRAY_SIZE(units) - 1; u++) {
> -		if (sz < SZ_1K)
> +		if ((sz & (SZ_1K - 1)) &&
> +		    sz < UPPER_UNIT_THRESHOLD * SZ_1K)
>  			break;
>  		sz = div_u64(sz, SZ_1K);
>  	}